anaerobes

Obligate anaerobe

Organisms that do not grow in the presence of oxygen.

Aerotolerant organisms

Organisms that grow best in anaerobic conditions but can tolerate up to 5% oxygen.

Facultative anaerobes

Organisms that can grow in both aerobic and anaerobic conditions.

Acceptable specimens for anaerobic cultures

Biopsies, body fluids, aspirates, and tissue.

Unacceptable specimens for anaerobic cultures

Sputum, swabs of superficial wounds, vaginal swabs, and urine.

Anaerobic culture storage

Plates are kept in anaerobic jars or bags until read in an anaerobic box or on the bench.

Brucella blood agar

Non-selective media that grows most anaerobic organisms and facultative anaerobes, contains vitamin K and hemin.

Bi Plate - LKV and BBE

Selective and differential media; LKV inhibits facultative organisms, while BBE allows bile-resistant organisms to grow.

Egg-Yolk agar

Media used to detect lecithinase and lipase production, as well as proteolysis.

Thioglycolate broth

A type of media used for anaerobic culture.

Clostridium perfringens

Gram-positive, boxcar-shaped bacilli that cause gangrene and food poisoning.

Clostridium tetani

Gram-positive bacilli with subterminal spores that produce a neurotoxin causing tetanus.

Clostridium botulinum

Produces a potent neurotoxin causing botulism, characterized by subterminal spores.

Clostridium difficile

Causes infections due to toxin production, often following antibiotic use.

Clostridium sordellii

gram-positive rods with subterminal spores, can swarm on brucella agar

Clostridium septicum

gram-positive rods, subterminal spores, swell cells, swarms, beta hemolytic, irregular rhizoid margins resembling a “medusa head”

Actinomyces

Filamentous branching gram-positive rods, “molar tooth” colonies, associated with periodontal disease and soft tissue infections.

Bifidobacterium

gram-positive diphtheroid, pointed or curved rods, branching, can have forked ends, “dog bones” or “Y” shaped, usually found in mixed pelvic or abdominal infections

Cutibacterium acnes

yellow, raised colonies, gram positive rods, can look diphtheroid-like, opportunistic pathogen, common blood culture contaminant

Eubacterium

gram-positive pleomorphic rods/coccobacilli, can have beading, filaments and branching

Lactobacillus

gram-positive pleomorphic rods/coccobacilli, can be aerobic or anaerobic, often a contaminant

Peptostreptococcus asaccharolyticus

GPC pairs, tetrads or irregular clusters

Peptostreptococcus anaerobius

gram-positive coccobacilli, chains, has a “sweet rotting” odor

Bacteroides fragilis

The most common cause of anaerobic infections, black on BBE agar.

Biophilia

pale staining, delicate gram-negative rods, can be black on BBE agar after 3-5 days, but disappears in the presence of O2

Prevotella

Normal oral flora with pigmented varieties that fluoresce brick red and are black on LKV

Porphyromonas

gram-negative coccobacilli, dark brown/black pigmented colonies that fluoresces brick red, causes gingivitis

Fusobacterium necrophorum

Virulent species causing various infections, gram-negative, pale staining, slender spindle-shaped rods, pointed ends, can be filamentous, fluoresces chartreuse

Fusobacterium nucleatum

gram-negative, pale staining, slender spindle shaped rods, pointed ends, bread crumb like colony, chartreuse fluorescent

Fusobacterium mortiferum

gram-negative, pale staining, filamentous rods, with swollen areas, “fried egg” colony

Mobiluncus

gram variable, small, thin, curved rods, very small colonies, normal vaginal flora

Veillonella

tiny gram-negative diplococci in clusters, pairs, or chains, can be found in mixed infections